Which of these is a characteristic of the state of equilibrium?

Options

A. Temperature is constant
B. `"Rate"_(f)="Rate"_(b)`
C. Conc. of reactants & products are constant
D. All of these

Answer

To determine the characteristics of the state of equilibrium, we need to analyze the options provided. Here’s a step-by-step solution to the question:

### Step 1: Understand the Concept of Equilibrium
Equilibrium in a chemical reaction is a state where the rates of the forward and backward reactions are equal, and the concentrations of reactants and products remain constant over time.

### Step 2: Analyze Each Option
1. **Temperature Constant**: In a system at equilibrium, if the temperature is constant, it indicates that the system is not undergoing any net change in energy. This is a characteristic of equilibrium.

2. **Rate of Forward Reaction Equals Rate of Backward Reaction**: At equilibrium, the rate at which reactants are converted to products (forward reaction) is equal to the rate at which products are converted back to reactants (backward reaction). This is another fundamental characteristic of equilibrium.

3. **Concentration of Reactants and Products is Constant**: At equilibrium, the concentrations of both reactants and products do not change. Although they may not be equal, their amounts remain constant over time.

### Step 3: Conclusion
Based on the analysis, all three statements are characteristics of the state of equilibrium:
- Temperature remains constant.
- The rate of the forward reaction equals the rate of the backward reaction.
- The concentration of reactants and products remains constant.

### Final Answer
All of the above options are characteristics of the state of equilibrium.

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